Modern transmissions, particularly in commercial vehicles, are increasingly controlled electronically; whereby the shift power is generated pneumatically or hydraulically, which improves the shift speed as well as the shift comfort. Transmissions of larger commercial vehicles are often divided into a main transmission, a split auxiliary transmission and a range auxiliary transmission. For example, this exhibits a pneumatically supported switch that executes the pneumatic gearshifts in split auxiliary transmissions and in regional-group gears; while the gearshifts in the main transmission could be supported by the synchronization with the help of the gear brakes at high shifts and with the help of motor for shift-in the executing force by pneumatic.
Such a switch for a gear is described in the DE 100 29 497 A1. This electro-pneumatic switch for a vehicle gear that exhibits a pneumatically shifted, split auxiliary transmission over valves and pneumatically shifted regional-group gear over a valve, requires an opening and a closing valve for each shift chamber of a switch cylinder that are linked to an air supply and an exhaust control with the cylinder chamber. If one of these valves fails then the functionality of these valves could not be changed for each cylinder chamber, whereby the availability of entire system is restricted and is not available in certain cases. Additionally, the dynamics of switch cylinder is very much limited.
The underlying task of the present patent is to represent an unrestricted availability of the switch also in case of valve failure, while not requiring thereby a solution involving complicated, failure contingent additional space. Further, the switch should improve the dynamic performance of the overall transmission system.